So How Do I... "Make" the Changes? (Part 3: Secondary Dominants)?

One of the most foundational skills that must be established early in an improviser's development is the ability to use melodies to clearly and accurately describe harmonies (or, "changes"). This process, often referred to as "making the changes", is one that causes many inexperienced jazz musicians a lot of confusion. This is the third in a series of posts in which I discuss four specific ways you can guide the listener's ear through jazz harmonies and thereby "make the changes".

3. Secondary Dominants

Tonality and Function

Like most all styles of Western music, jazz developed within the European system of major/minor tonality. This system dates back to the 18th century and allows for music to be organized into any of 12 major and 12 minor keys. Within a given major or minor key, every note and chord are functioning with a specific role regarding the conveyance of stability or instability. In my first post of this series, I illustrated that not all the notes in a given scale are functioning with equal importance. Certain notes (Root, 3rd, 5th) play a more significant role at defining the scale's major or minor tonality than others (2nd, 4th, 6th, 7th). Part of the purpose of this post is to illustrate that this same principle is also at work within the diatonic harmonies of a major or minor key.

To begin, let's take a look at the diatonic 7th chord harmonies in the key of C major.

The chord symbols above the staff describe what each 7th chord is, whereas the roman numerals below the staff designate how each of these chords is functioning within the context of the key. For example, the ii-7 chord in the above example is a D-7. If we were in the key of F major, however, that same D-7 chord would be the vi-7 chord. If we were in the key of A minor, that same D-7 would be the iv-7 chord. This goes to show that within different tonal contexts, the same chord can take on a number of different functions.

Now, of all these diatonic chords, the two most important at defining and establishing the key are the G7 (V) and Cmaj7 (I) chords. The V and I chords embody the Stability-Instability duality of the major/minor tonal system, and all other diatonic chords assist them in their roles of creating tension and release within the music. This is simple enough to understand when dealing with major keys, but it becomes slightly more complicated in minor keys. In minor key signatures, the 7th scale degree is the subtonic, which is a whole step below the tonic. This creates the problem of not having access to a leading tone. And if we have no leading tone, we can't have a V7 chord. And if we have no V7 chord, then we can have no V7-I/i movement. And as I just stated, the V7-I/i movement is the most important harmonic movement in defining and establishing keys. Therefore, when constructing diatonic harmonies (and often when constructing melodies) in minor keys, the 7th scale degree is raised a half step in order to create a leading tone in the V7 chord that will pull towards the tonic. Doing this creates a Harmonic Minor Scale. These diatonic harmonies are illustrated below in the key of C minor.

Thus, we can see that in major and minor keys, not all diatonic chords are functioning the same way, and among these different functions, the relationship between the dominant V7 chord and tonic I/i chord is the most important at defining and identifying the key and tonality. Above, we noted how the same chord can take on different functions depending on the key it is residing in. Minor 7th chords can be ii chords, iii chords, vi chords, and iv chords. Major 7 chords can be I chords, IV chords, and bVI chords. What about a dominant 7th chord? How many functions can a chord of that quality take on? Only one: V7! In the world of jazz, blues, rock, and other "contemporary" styles, dominant 7th chords can function as I chords and IV chords, but aside from these specific instances, dominant 7th chords are exclusively used as V chords to tonicize or "point to" tonic chords.

Secondary Dominants

So what does all this have to do with secondary dominants? Well, oftentimes when we are playing a piece of music, we encounter dominant 7th chords which are not the primary dominant chord in the key we are in. For example, say we're playing a tune in the key of C major (the primary dominant of which is G7) and we come across an E7 chord and an A7 chord.

Even though the notes E and A are in the key of C major, the diatonic 7th chords built off of those notes are minor 7th chords (E-7 & A-7). Thus, the E7 and A7 in the tune can not be functioning as iii and ii in the key of C major. So what's the deal with these chords? How are they functioning? Well, given the fact that we decided dominant 7th chords are (almost) always acting as V7 chords, we can conclude that these chords are functioning as V7 chords of keys that are not C major. Thus, "secondary" dominants.

To fully understand this concept, it is important to realize that music can occur in any of the 12 major and 12 minor keys, and oftentimes a piece of music in one of those keys will hint at another one of the keys by "borrowing" chords from the other key. So just because a piece of music is in the key of C major doesn't mean that the only chords used in the piece will be the 7 diatonic chords in the key of C major. Chords can be borrowed from other keys to create chromatic color and developmental interest.

So where are the chords in the above example being borrowed from? Well, we've decided that they are functioning as V7 chords, but things get a little more complicated when we realize that V7 chords are the same in both major and minor keys. So E7 is V7 of both A major and A minor, and A7 is V7 of both D major and D minor. How do we know if these chords are "pointing to" the major keys or the minor keys? That's a good question, especially given the fact that secondary dominants oftentimes do not resolve to the tonic chords they are associated with (like the E7 in the example above). The most commonly-used secondary dominants are those of the key's closely-related keys. The closely-related keys of a key are the keys whose tonics are the diatonic triads of the key. Here's an example to help illustrate this point:

The above example shows that the closely-related keys to C major are D minor, E minor, F major, G major, and A minor. A diminished triad can't function as the tonic of a key, so that's why we leave out B diminished.

So to get back to our question, "How do we know if E7 and A7 are 'pointing to' major keys or minor keys?". The answer would be, "It is most natural the hear these chords as tonicizing closely-related keys to C major, so they are therefore 'pointing to' the keys A minor and D minor."

Now that we have laid some groundwork and understand what secondary dominants are, let's discuss how we can melodically deal with them when taking an improvised solo. Our approach here is not going to be thinking of any sort of chord/scale relationships, but rather, chord/key relationships. For V7 chords associated with major keys, we're going to be thinking of the major key the V7 points to, and for V7 chords associated with minor keys, we're going to be thinking of the harmonic minor key the V7 points to (because we want to be sure the leading tone is present). However, out of all the notes in the key, we specifically want to isolate the chromatic notes that are not present within the home key. This will most efficiently and effectively identify the chromatic sound that the secondary dominant is implying. The example below illustrates this idea.

In the example, each measure represents a different key--the first being the home key of C major. The text below the measures indicates the key that is represented (again, for minor keys, harmonic minor is being used), and the chord symbols above the measures indicate the dominant chord of that key, which would all be secondary dominants to the key of C major (except the G7). The notes in each measure are the notes of the key that are chromatic to the key of C major. Introducing these notes to your improvised line will strongly convey the "secondary dominant"-ness of the non-diatonic chords.

To illustrate this, the following three examples demonstrate eighth-note lines over three common jazz progressions that use secondary dominants: the first four bars of "All of Me", the first four bars of "Someday My Prince Will Come", and a couple ii-V-I-V/ii progressions. In each example, the eighth-note lines played over the secondary dominant chords are bracketed and labeled according to which key the chord is acting as dominant within. Parenthesized are the notes chromatic to the key that are part of each Harmonic minor key. Play through the examples and hear how effectively these parenthesized "goal notes" melodically describe the secondary dominant.

All of Me

Someday My Prince Will Come

ii-V-I-V/ii

Practice Suggestions

So how can one further internalize the ideas discussed in this post and begin improvising more clearly over secondary dominants?

Have a rock-solid knowledge of all major and harmonic minor scales. At the heart of the principle of secondary dominants is the idea that music occurs in all keys, and oftentimes music changes (or pretends to change) keys in the middle of a song. Therefore, as improvisers we must be prepared to play in all 12 major and 12 minor keys.

Be able to play the 5th mode of all harmonic minor scales. The fifth mode of the major scale (Mixolydian mode) is one of the most commonly-used major scale modes, and its usefulness at defining V7 chords in major keys is one of the first things developing improvisers learn. Its corresponding scale at defining V7 chords in minor keys is the 5th mode of the harmonic minor scale. This scale is sometimes referred to as "Mixolydian b2 b6", or "Phrygian Dominant". This scale is an important one to know because very often secondary dominants are pointing to minor tonics.

Practice functionally analyzing chord progressions. In order to improvise in the correct keys over secondary dominants, one must understand what keys the secondary dominants are pointing to. Familiarize yourself with the diatonic harmonies of major and minor keys, and understand how different chord qualities can function in those keys. Understand which are the closely-related keys of any given key, and be able to draw connections between closely-related keys and the secondary dominants of those keys.

Practice identifying the chromatic "goal notes" of closely-related keys. What notes are different between Bb major and C minor? What about between Eb major and G minor? F major and Bb major? Being able to identify these chromatic differences will help you make in-the-moment decisions on how to clearly transition from Bbmaj7 to G7; from Ebmaj7 to G7; or from Fmaj7 to F7.

Hopefully these thoughts on improvising over secondary dominants have helped. Do you have any special tips or tricks that help you navigate secondary dominants? Leave your comments below!